Adjustable inductance unit



1965 J. R. GELZER ETAL 25,334

ADJUSTABLE mnucmnca 1mm Original Filed Nov. 3, 1958 IN V EN TORS c/OF/A/R. 621.22? ml By Riel-M O E REED FL-FE 5- United States Patent 25,834ADJUSTABLE INDUCTANCE UNIT John R. Gelzer, Barrington, Ill., and RichardF. Reed,

Bloomington, Ind., assignors to Sarkes Tarzian, Incorporated,Bloomington, Ind., a corporation of Indiana Original No. 2,989,710,dated June 20, 1961, Ser. No.

771,418, Nov. 3, 1958. Application for reissue June 18,

1963, Ser. No. 289,464

9 Claims. (Cl. 336-) Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

The present invention relates to adjustable inductance units and it moreparticularly relates to adjustable inductance units which may bedirectly mounted on the selector switches of VHF television tuners.

According to present day standards, the VHF, or very high frequencytelevision band, is divided into a lower VHF band comprising channels 2through 6, inclusive, and extending from 54 to 88 megacycles and a highfrequency VHF band comprising channels 7 through 13, inclusive, andextending from 174 to 216 megacycles. In switch type VHF televisiontuners it is customary to connect inductance increments between adjacentones of twelve contacts on rotary switches having twelve VHF channelselecting positions. The inductance increments may thus be selectivelyand accumulatively added to the various tuned circuits of the tuner toselectively tune them to the frequencies assigned to each of the twelveVHF channels. Inasmuch as each television channel, whether in the higheror lower VHF television bands, occupies a bandwidth of 6 megacycles, theinductance increments used for switching between the higher bandchannels have a considerably lower inductance value than do theincremental inductances used for switching between the channels in thelower VHF band. While the exact inductance values used depends upon therequirements of the circuits used in the particular tuner, the lowerband channel incremental inductances are ordinarily provided by air corecoils having at least five turns while the higher band inductanceincrements are provided by coils comprising a single turn or less. Sincethe lower band inductances utilize a substantial number of turns, theycan be readily adjusted by deforming their shape until the desiredinductance value is provided but a similar adjustment of the single turncoil of the higher band inductances is substantially more difficult andthe range of adjustment is very much limited. Therefore, a seriousproblem confronting the designers of VHF television tuners has been theprovision of adjustable inductance increments for channel switching inthe higher VHF band. Of course, the manufacturing cost of televisiontuners is always an important factor to be considered and any meansemploying such switching must have a cost commensurate with the cost ofthe other components in the tuner. By way of example, an integralinductance unit for the entire high frequency band has been provided inthe past by means of a metallic stamping and adjustability of theinductance value between adjacent contacts was effected by a pluralityof adjustable slugs threadedly connected to the stampings betweenadjacent contacts. While such an arrangement lends itself to rapid andaccurate assembly of the tuner switch, its manufacturing cost is veryhigh, and therefore, it is an object of this invention to provide a lessexpensive and yet equally good incremental inductance unit for switchingbetween the channels in the higher VHF television band.

Another object of the present invention is to provide a new and improvedincremental inductance unit suitable for use in VHF television tuners ofthe switch type.

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Another object of the present invention is to provide a new and improvedmultiple contact rotary switch for use in VHF television tuners.

A further object of the present invention is to provide a new andimproved incremental inductance unit which is simple in construction,low in manufacturing cost and which enables individual adjustment of aplurality of inductive increments thereof throughout a sufficiently widerange of inductance values to insure satisfactory switching betweentelevision channels in the upper VHF television band.

Briefly, the above and further objects are realized in accordance withthe present invention by providing a multiple inductance unit which canbe easily mounted on a rotary selector switch to provide a plurality ofadjustable inductance increments between adjacent ones of a number ofthe stator contacts of the switch. The inductance unit preferablycomprises a soft metal stamping having an arcuate body portion, aplurality of inwardly directed radial protrusions, and a plurality ofcontact tabs interposed between the protrusions. The tabs are adapted tobe connected to the stator contacts of the switch and the protrusionsextend a substantial distance between the contacts toward the center ofthe switch. The unit is stamped from a flat metal sheet and at theoutset the arcuate body portion and the radial protrusions are both flatand lie in a common plane. Inasmuch as the protrusions and the body aresoft, the inductance values connected between adjacent contacts of theswitch can be adjusted by bending the protrusions out of the plane ofthe body and out of the space directly between the contacts. Moreover,since the protrusions and the body are planar, a relatively large rangeof adjustment is provided.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following detailed description taken inconnection with the accompanying drawings, in which:

FIG. 1 is a plan view of a multiple contact rotary switch embodying thepresent invention;

FIG. 2 is a cross sectional view of the switch of FIG. 1 taken along theline 2-2 thereof; and

FIG. 3 is a greatly enlarged fragmentary view of a portion of FIG. 2showing the connection between the switch contact and the incrementalinductance unit.

Referring now to the drawings and particularly to FIG. 1 thereof, thereis shown a multiple contact rotary switch 10 which comprises as itsprincipal parts an insulating stator wafer 11, a rotor 12 which isjournaled in a central aperture in the wafer 11, and a set of contacts13 which are mounted on the wafer 11. The contacts 13 each include aninwardly directed contact portion 15 which is selectively engaged by anirregularly shaped conductive wiper 16 mounted on the rotor 12. Thecontacts 13 comprise a first group of contacts 13a, 13b, 13c, 13d, and13e, which are used for selective switching between the channels in thelower VHF television band, and therefore, a plurality of inductancecoils (not shown) may be connected between adjacent ones of the contacts1321 through 13c, inclusive. The contacts 13 further comprise a secondgroup of ocntacts 13f, 13g, 13h, 13i, 13j, 13k, and Bi, which are usedfor switching between the channels in the higher VHF television band. Athirteenth contact, designated 13m, may be used to adapt the tuner foruse in a UHF tuner, in which case the contact 13m is selectivelyconnected to the wiper 16 when the switch 10 is in the UHF signalreceiving position.

In order to provide the inductance increments necessary to enableswitching between the channels in the high VHF television hand, there isprovided in accordance with the present invention an incrementalinductance unit 20 which is stamped from a sheet of soft metal, such ascopper, and which comprises an arcuate body portion 21 from which aplurality of contact tabs 22 extend. As best shown in FIGS. 2 and 3, thetabs 22 are L-shaped in cross section, having a first portion which isimmediately adjacent to and coplanar with the body 21 and which extendstoward the axis of rotation of the rotor 12. Preferably, the body 21 isconcentric with the arc on which the contact clips 13 are mounted. Themarginal end portion of the tabs 22 depend into apertures 24 provided inthe stator wafer 11. The terminals 25 of the contact clips 13 alsodepend through the apertures 24, and the tabs 22 and terminals arecoupled together by means of a solder connection 26 provided on thelower side of the stator 11. Since the contact clips 13 are eyeleted tothe wafer 11, the conductive increment unit 20 is thereby secured to thewafer 11.

In order to provide an adjustable inductance value between adjacent onesof the contact clips 13, the inductance unit 20 further includes aplurality of inwardly directed radial protrusions 28 which areinterposed between the tabs 22 and extend a substantial distance betweenthose contact clips 13 which are connected to the tabs 22. Inasmuch asthe unit 20 is stamped from a sheet of soft metal, the protrusions 28may be readily bent up out of the plane of the body 21 and thus out ofthe space directly between the adjacent contact clips 13, thereby toadjust the value of inductance connected between these contact clips 13.

In order to facilitate bending of the protrusions 28 for adjustment ofthe inductance values, each of the protrusions is provided with agenerally triangular aperture 29 which extends to the body 21.Accordingly, the protrusions 28 are generally V-shaped and connected tothe are 21 by relatively narrow sections 30 and 31 whereby theprotrusions 28 may be easily and accurately bent or deflected to thedesired position. It is particularly desirable that the metal from whichthe inductance unit 28 is formed be soft and not resilient so that itwill take a permanent set very readily in whatever position theprotrusions 28 are placed during adjustment. This eliminates guessworkin the adjustment of the inductance values during alignment of thetuner.

It will be understood that since the inductance values required willvary from one tuner design to another as well as between stages of thesame tuner, different sized protrusions 28 and different sized apertures29 may be selected to provide whatever inductance values are required.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be understood thatvarious modifications may be made therein which are within the truespirit and scope of the invention as defined in the appended claims.

What is claimed as new and is desired to be secured by Letters Patent ofthe United States is:

1. In a television tuner, the combination of a multiple contact rotaryswitch for adjusting in discrete increments the tuning of a tunedcircuit in said tuner, said switch including a plurality of arcuatelydisposed contact clips, and a generally arcuate stamping formed of asoft, nonresilient metal, said stamping being flat and including aplurality of first inwardly directed radial portions connected torespective ones of said contacts and a plurality of second inwardlydirected incremental inductance portions interposed between said firstportions and extending a substantial distance between said contacts.

2. A multiple contact rotary switch for use in a high frequency tuner,comprising an insulating stator wafer, a wiper rotatably mounted on saidwafer, a plurality of contacts mounted on said wafer for selectiveengagement by said Wiper, said contacts being arcuately disposed on saidwafer, and an adjustable inductance member, said member having agenerally arcuate connecting portion spanning a plurality of saidcontacts and disposed beyond the ends thereof, said member furtherhaving a plurality of inwardly directed tabs respectively connected tosaid spanned contacts and a plurality of inwardly directed adjustableprotrusions interposed between said tabs, said latter portionscomprising incremental inductances and being relatively soft andbendable so as to permit adjustment of the inductance values betweenadjacent ones of said spanned contacts.

3. A multiple contact rotary switch comprising an annular stator wafermade of an insulating material, a wiper rotatably mounted on said wafer,a plurality of contact clips riveted to said wafer on one face thereof,said clips being selectively engageable by said wiper, said statorincluding a plurality of. apertures respectively disposed along theradii on which said clips are positioned, the end portions of said clipsdepending through said apertures and protruding beyond the opposite faceof said stator, and an incremental inductance member of generallyarcuate configuration, said member including a plurality of spatiallydisposed otlset tabs respectively depending through said apertures andconnected to said clips on said opposite side of said stator water.

4. In a television tuner, the combination of a multiple contact rotaryswitch including a rotor and a stator on which a plurality of contactsare mounted for selective engagement by said rotor, a generally arcuatemetal stamping mounted on said stator, said stamping comprising anarcuate portion disposed beyond the ends of a plurality of saidcontacts, a plurality of tabs extending from said arcuate portion atsubstantial right angles thereto and respectively depending intoapertures in said stator through which portions of said contacts alsorespectively depend, said tabs being soldered to said contacts to securesaid stamping to said switch and to connect said plurality of saidcontacts to spatially disposed locations on said arcuate portion, saidstamping further comprising a plurality of radially extending V-shapedinductive increments respectivelly interposed between said tabs and atleast partially disposed between adjacent ones of said plurality ofcontacts, said increments being substantially planar and pivotable outof the plane of said arcuate portion thereby to provide, between saidplurality of contacts, inductive increments of adjustable value.

5. A multiple inductance stamping for connection to a multiple contactrotary switch used in a television tuner, comprising a flat arcuateportion, a plurality of spatially disposed tabs protruding from saidarcuate portion, said tabs lying substantially transverse to the planeof said arcuate portion, and a plurality of inductive incrementsintegral with said arcuate portion and disposed between said tabs, saidincrements extending toward the central axis of said arcuate portion,said stamping being metal and the connection of said increments to saidarcuate portion being sufficiently flexible to permit manual bending ofsaid increments with respect to the plane of said arcuate portion toadjust the inductance value of said increments.

6. In a multpile contact rotary switch for use in a high frequency tunerwhich includes an insulating stator wafer and a wiper rotatably mountedon said wafer, a stator contact and incremental inductance assemblycomprising, a plurality of stator contact members arcuately disposed onsaid wafer for selective engagement by said wiper, and an adjustableincremental inductance member, said inductance member having a generallyarcuate peripheral portion spanning a plurality of said stator contactmembers and connected to said spanned contact members by inwardlydirected connecting portions, said inductance member also having aplurality of inwardly directed adiustnble protrusions interposed betweensaid connecting portions and consitztuting incremental inductanceportions which are relatively soft and bendable so as to permitadjustment of the inductance values between adjacent ones of saidspanned stator contact members.

7. In a multiple Contact rotary switch for use in a high frequency tunerwhich includes an insulating stator wafer and a wiper rotatably mountedon said wafer, a

stator contact and incremental inductance assembly comprising, aplurality of stator contact members arcuately disposed on said wafer forselective engagement by said wiper, and an adjustable incrementalinductance memher, said inductance member having a generally arcuateperipheral portion spanning a plurality of said stator contact membersand connected to said spanned contact members by inwardly directedconnecting portions, said inductance member being formed of soft,non-resilient sheet metal and also including a plurality of inductiveincrement portions disposed between said connecting portions, theconnection of said increment portions to said inductance member beingsufliciently flexible to permit bending of said increment portions withrespect to the plane of said inductance member to adjust the inductancevalue of said increment portions.

8. In a multiple contact rotary switch for use in a high frequency tunerwhich includes an insulating stator wafer and a wiper rotatably mountedon said wafer, a stator contact and incremental inductance assemblycomprising, a plurality of stator contact members arcuately disposed onsaid wafer for selective engagement by said wiper, and an incrementalinductance plate member, said inductance plate having a generallyarcuate peripheral portion spanning a plurality of said stator contactmembers and connected to said spanned contact members by inwardlydirected connecting portions, said inductance plate being formed ofsoft, non-resilient metal and including a plurality of inductiveincrement portions connected to said arcuate portion and disposedbetween said connecting portions, said inductive increment portionsextending toward the central axis of said arcuate portion and theconnection of said increment portions to said arcuate portion beingsufficiently flexible to permit bending of said increment portions withrespect to the plane of said inductance plate to adjust the inductancevalues between adjacent ones of said spanned stator contact members.

9. In a multiple contact rotary switch for use in a high frequency tunerwhich includes an insulating stator wafer and a wiper rotatably mountedon said wafer, a stator contact and incremental inductance assemblycomprising, a plurality of stator contact members arcuately disposed onsaid wafer for selective engagement by said wiper, and an incrementalinductance plate member, said inductance plate having a generallyarcuate peripheral portion spanning a plurality of said stator contactmembers and connected to said spanned contact members by inwardlydirected connecting portions, said inductance plate being formed ofsoft, non-resilient metal and having a plurality of apertures definingincremental inductance loop portions connected to said arcuate portionand disposed between said connecting portions, said inductive incrementloop portions extending toward the central axis of said arcuate portionand the connection of said increment loop portions to said arcuateportion being sufi'iciently flexible to permit bending of said incrementloop portions with respect to the plane of said inductance plate toadjust the inductance values between adjacent ones of said spannedstator contact members.

References Cited by the Examiner JOHN F. BURNS, Primary Examiner.

MILTON O. HIRSHFIELD, Examiner.

